OBJECTIVES: Determine the risk factors involved in toxoplasmosis transmission and determine whether pregnancy is a risk factor for toxoplasmosis infection. STUDY DESIGN: Cross-sectional study carried out on 2,242 women at childbearing age. An indirect immunofluorescence reaction was used to identify immunity to Toxoplasma gondii. Previous gestations were also analyzed as a possible risk factor. The results were analyzed by c2 and OR tests, and by variance analysis. The sample was statistically balanced according to social-economic risk factors. RESULTS: Previously pregnant women were 1.74 times more frequently infected with toxoplasmosis, regardless of environmental conditions. Pregnant women living under unfavorable environmental conditions had an approximately two times increased risk of being infected for each risk factor (contact with host animals, presence of vehicles of oocyst transmission). Previous pregnancy was the risk factor that had the strongest influence on acquiring toxoplasmosis (variance analysis and statistical balancing). DISCUSSION: The prevalence of this zoonosis is high in Goiânia-GO, Brazil (65.8%). Inadequate environmental sanitation was not significantly correlated with toxoplasmosis infection, except when associated with previous pregnancy, showing that the fundamental cause for infection is not environmental. CONCLUSION: The finding that pregnancy makes women more vulnerable to this protozoan, makes it important to implement prophylactic control of at-risk pregnant women.